summaryrefslogtreecommitdiff
path: root/fs/pstore/blk.c
blob: a9e7078f08d683b74d1efe8f0ab212a6e7d091df (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
// SPDX-License-Identifier: GPL-2.0
/*
 * Implements pstore backend driver that write to block (or non-block) storage
 * devices, using the pstore/zone API.
 */

#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt

#include <linux/kernel.h>
#include <linux/module.h>
#include "../../block/blk.h"
#include <linux/blkdev.h>
#include <linux/string.h>
#include <linux/of.h>
#include <linux/of_address.h>
#include <linux/platform_device.h>
#include <linux/pstore_blk.h>
#include <linux/mount.h>
#include <linux/uio.h>

static long kmsg_size = CONFIG_PSTORE_BLK_KMSG_SIZE;
module_param(kmsg_size, long, 0400);
MODULE_PARM_DESC(kmsg_size, "kmsg dump record size in kbytes");

static int max_reason = CONFIG_PSTORE_BLK_MAX_REASON;
module_param(max_reason, int, 0400);
MODULE_PARM_DESC(max_reason,
		 "maximum reason for kmsg dump (default 2: Oops and Panic)");

#if IS_ENABLED(CONFIG_PSTORE_PMSG)
static long pmsg_size = CONFIG_PSTORE_BLK_PMSG_SIZE;
#else
static long pmsg_size = -1;
#endif
module_param(pmsg_size, long, 0400);
MODULE_PARM_DESC(pmsg_size, "pmsg size in kbytes");

/*
 * blkdev - the block device to use for pstore storage
 *
 * Usually, this will be a partition of a block device.
 *
 * blkdev accepts the following variants:
 * 1) <hex_major><hex_minor> device number in hexadecimal representation,
 *    with no leading 0x, for example b302.
 * 2) /dev/<disk_name> represents the device number of disk
 * 3) /dev/<disk_name><decimal> represents the device number
 *    of partition - device number of disk plus the partition number
 * 4) /dev/<disk_name>p<decimal> - same as the above, that form is
 *    used when disk name of partitioned disk ends on a digit.
 * 5) PARTUUID=00112233-4455-6677-8899-AABBCCDDEEFF representing the
 *    unique id of a partition if the partition table provides it.
 *    The UUID may be either an EFI/GPT UUID, or refer to an MSDOS
 *    partition using the format SSSSSSSS-PP, where SSSSSSSS is a zero-
 *    filled hex representation of the 32-bit "NT disk signature", and PP
 *    is a zero-filled hex representation of the 1-based partition number.
 * 6) PARTUUID=<UUID>/PARTNROFF=<int> to select a partition in relation to
 *    a partition with a known unique id.
 * 7) <major>:<minor> major and minor number of the device separated by
 *    a colon.
 */
static char blkdev[80] = CONFIG_PSTORE_BLK_BLKDEV;
module_param_string(blkdev, blkdev, 80, 0400);
MODULE_PARM_DESC(blkdev, "block device for pstore storage");

/*
 * All globals must only be accessed under the pstore_blk_lock
 * during the register/unregister functions.
 */
static DEFINE_MUTEX(pstore_blk_lock);
static struct block_device *psblk_bdev;
static struct pstore_zone_info *pstore_zone_info;
static pstore_blk_panic_write_op blkdev_panic_write;

struct bdev_info {
	dev_t devt;
	sector_t nr_sects;
	sector_t start_sect;
};

/**
 * struct pstore_device_info - back-end pstore/blk driver structure.
 *
 * @total_size: The total size in bytes pstore/blk can use. It must be greater
 *		than 4096 and be multiple of 4096.
 * @flags:	Refer to macro starting with PSTORE_FLAGS defined in
 *		linux/pstore.h. It means what front-ends this device support.
 *		Zero means all backends for compatible.
 * @read:	The general read operation. Both of the function parameters
 *		@size and @offset are relative value to bock device (not the
 *		whole disk).
 *		On success, the number of bytes should be returned, others
 *		means error.
 * @write:	The same as @read.
 * @panic_write:The write operation only used for panic case. It's optional
 *		if you do not care panic log. The parameters and return value
 *		are the same as @read.
 */
struct pstore_device_info {
	unsigned long total_size;
	unsigned int flags;
	pstore_zone_read_op read;
	pstore_zone_write_op write;
	pstore_zone_write_op panic_write;
};

static int psblk_register_do(struct pstore_device_info *dev)
{
	int ret;

	if (!dev || !dev->total_size || !dev->read || !dev->write)
		return -EINVAL;

	mutex_lock(&pstore_blk_lock);

	/* someone already registered before */
	if (pstore_zone_info) {
		mutex_unlock(&pstore_blk_lock);
		return -EBUSY;
	}
	pstore_zone_info = kzalloc(sizeof(struct pstore_zone_info), GFP_KERNEL);
	if (!pstore_zone_info) {
		mutex_unlock(&pstore_blk_lock);
		return -ENOMEM;
	}

	/* zero means not limit on which backends to attempt to store. */
	if (!dev->flags)
		dev->flags = UINT_MAX;

#define verify_size(name, alignsize, enabled) {				\
		long _##name_ = (enabled) ? (name) : 0;			\
		_##name_ = _##name_ <= 0 ? 0 : (_##name_ * 1024);	\
		if (_##name_ & ((alignsize) - 1)) {			\
			pr_info(#name " must align to %d\n",		\
					(alignsize));			\
			_##name_ = ALIGN(name, (alignsize));		\
		}							\
		name = _##name_ / 1024;					\
		pstore_zone_info->name = _##name_;			\
	}

	verify_size(kmsg_size, 4096, dev->flags & PSTORE_FLAGS_DMESG);
	verify_size(pmsg_size, 4096, dev->flags & PSTORE_FLAGS_PMSG);
#undef verify_size

	pstore_zone_info->total_size = dev->total_size;
	pstore_zone_info->max_reason = max_reason;
	pstore_zone_info->read = dev->read;
	pstore_zone_info->write = dev->write;
	pstore_zone_info->panic_write = dev->panic_write;
	pstore_zone_info->name = KBUILD_MODNAME;
	pstore_zone_info->owner = THIS_MODULE;

	ret = register_pstore_zone(pstore_zone_info);
	if (ret) {
		kfree(pstore_zone_info);
		pstore_zone_info = NULL;
	}
	mutex_unlock(&pstore_blk_lock);
	return ret;
}

static void psblk_unregister_do(struct pstore_device_info *dev)
{
	mutex_lock(&pstore_blk_lock);
	if (pstore_zone_info && pstore_zone_info->read == dev->read) {
		unregister_pstore_zone(pstore_zone_info);
		kfree(pstore_zone_info);
		pstore_zone_info = NULL;
	}
	mutex_unlock(&pstore_blk_lock);
}

/**
 * psblk_get_bdev() - open block device
 *
 * @holder:	Exclusive holder identifier
 * @info:	Information about bdev to fill in
 *
 * Return: pointer to block device on success and others on error.
 *
 * On success, the returned block_device has reference count of one.
 */
static struct block_device *psblk_get_bdev(void *holder,
					   struct bdev_info *info)
{
	struct block_device *bdev = ERR_PTR(-ENODEV);
	fmode_t mode = FMODE_READ | FMODE_WRITE;
	sector_t nr_sects;

	lockdep_assert_held(&pstore_blk_lock);

	if (pstore_zone_info)
		return ERR_PTR(-EBUSY);

	if (!blkdev[0])
		return ERR_PTR(-ENODEV);

	if (holder)
		mode |= FMODE_EXCL;
	bdev = blkdev_get_by_path(blkdev, mode, holder);
	if (IS_ERR(bdev)) {
		dev_t devt;

		devt = name_to_dev_t(blkdev);
		if (devt == 0)
			return ERR_PTR(-ENODEV);
		bdev = blkdev_get_by_dev(devt, mode, holder);
		if (IS_ERR(bdev))
			return bdev;
	}

	nr_sects = part_nr_sects_read(bdev->bd_part);
	if (!nr_sects) {
		pr_err("not enough space for '%s'\n", blkdev);
		blkdev_put(bdev, mode);
		return ERR_PTR(-ENOSPC);
	}

	if (info) {
		info->devt = bdev->bd_dev;
		info->nr_sects = nr_sects;
		info->start_sect = get_start_sect(bdev);
	}

	return bdev;
}

static void psblk_put_bdev(struct block_device *bdev, void *holder)
{
	fmode_t mode = FMODE_READ | FMODE_WRITE;

	lockdep_assert_held(&pstore_blk_lock);

	if (!bdev)
		return;

	if (holder)
		mode |= FMODE_EXCL;
	blkdev_put(bdev, mode);
}

static ssize_t psblk_generic_blk_read(char *buf, size_t bytes, loff_t pos)
{
	struct block_device *bdev = psblk_bdev;
	struct file file;
	struct kiocb kiocb;
	struct iov_iter iter;
	struct kvec iov = {.iov_base = buf, .iov_len = bytes};

	if (!bdev)
		return -ENODEV;

	memset(&file, 0, sizeof(struct file));
	file.f_mapping = bdev->bd_inode->i_mapping;
	file.f_flags = O_DSYNC | __O_SYNC | O_NOATIME;
	file.f_inode = bdev->bd_inode;
	file_ra_state_init(&file.f_ra, file.f_mapping);

	init_sync_kiocb(&kiocb, &file);
	kiocb.ki_pos = pos;
	iov_iter_kvec(&iter, READ, &iov, 1, bytes);

	return generic_file_read_iter(&kiocb, &iter);
}

static ssize_t psblk_generic_blk_write(const char *buf, size_t bytes,
		loff_t pos)
{
	struct block_device *bdev = psblk_bdev;
	struct iov_iter iter;
	struct kiocb kiocb;
	struct file file;
	ssize_t ret;
	struct kvec iov = {.iov_base = (void *)buf, .iov_len = bytes};

	if (!bdev)
		return -ENODEV;

	/* Console/Ftrace backend may handle buffer until flush dirty zones */
	if (in_interrupt() || irqs_disabled())
		return -EBUSY;

	memset(&file, 0, sizeof(struct file));
	file.f_mapping = bdev->bd_inode->i_mapping;
	file.f_flags = O_DSYNC | __O_SYNC | O_NOATIME;
	file.f_inode = bdev->bd_inode;

	init_sync_kiocb(&kiocb, &file);
	kiocb.ki_pos = pos;
	iov_iter_kvec(&iter, WRITE, &iov, 1, bytes);

	inode_lock(bdev->bd_inode);
	ret = generic_write_checks(&kiocb, &iter);
	if (ret > 0)
		ret = generic_perform_write(&file, &iter, pos);
	inode_unlock(bdev->bd_inode);

	if (likely(ret > 0)) {
		const struct file_operations f_op = {.fsync = blkdev_fsync};

		file.f_op = &f_op;
		kiocb.ki_pos += ret;
		ret = generic_write_sync(&kiocb, ret);
	}
	return ret;
}

static ssize_t psblk_blk_panic_write(const char *buf, size_t size,
		loff_t off)
{
	int ret;

	if (!blkdev_panic_write)
		return -EOPNOTSUPP;

	/* size and off must align to SECTOR_SIZE for block device */
	ret = blkdev_panic_write(buf, off >> SECTOR_SHIFT,
			size >> SECTOR_SHIFT);
	return ret ? -EIO : size;
}

static int __register_pstore_blk(struct pstore_blk_info *info)
{
	char bdev_name[BDEVNAME_SIZE];
	struct block_device *bdev;
	struct pstore_device_info dev;
	struct bdev_info binfo;
	void *holder = blkdev;
	int ret = -ENODEV;

	lockdep_assert_held(&pstore_blk_lock);

	/* hold bdev exclusively */
	memset(&binfo, 0, sizeof(binfo));
	bdev = psblk_get_bdev(holder, &binfo);
	if (IS_ERR(bdev)) {
		pr_err("failed to open '%s'!\n", blkdev);
		return PTR_ERR(bdev);
	}

	/* only allow driver matching the @blkdev */
	if (!binfo.devt || MAJOR(binfo.devt) != info->major) {
		pr_debug("invalid major %u (expect %u)\n",
				info->major, MAJOR(binfo.devt));
		ret = -ENODEV;
		goto err_put_bdev;
	}

	/* psblk_bdev must be assigned before register to pstore/blk */
	psblk_bdev = bdev;
	blkdev_panic_write = info->panic_write;

	/* Copy back block device details. */
	info->devt = binfo.devt;
	info->nr_sects = binfo.nr_sects;
	info->start_sect = binfo.start_sect;

	memset(&dev, 0, sizeof(dev));
	dev.total_size = info->nr_sects << SECTOR_SHIFT;
	dev.flags = info->flags;
	dev.read = psblk_generic_blk_read;
	dev.write = psblk_generic_blk_write;
	dev.panic_write = info->panic_write ? psblk_blk_panic_write : NULL;

	ret = psblk_register_do(&dev);
	if (ret)
		goto err_put_bdev;

	bdevname(bdev, bdev_name);
	pr_info("attached %s%s\n", bdev_name,
		info->panic_write ? "" : " (no dedicated panic_write!)");
	return 0;

err_put_bdev:
	psblk_bdev = NULL;
	blkdev_panic_write = NULL;
	psblk_put_bdev(bdev, holder);
	return ret;
}

/**
 * register_pstore_blk() - register block device to pstore/blk
 *
 * @info: details on the desired block device interface
 *
 * Return:
 * * 0		- OK
 * * Others	- something error.
 */
int register_pstore_blk(struct pstore_blk_info *info)
{
	int ret;

	mutex_lock(&pstore_blk_lock);
	ret = __register_pstore_blk(info);
	mutex_unlock(&pstore_blk_lock);

	return ret;
}
EXPORT_SYMBOL_GPL(register_pstore_blk);

static void __unregister_pstore_blk(unsigned int major)
{
	struct pstore_device_info dev = { .read = psblk_generic_blk_read };
	void *holder = blkdev;

	lockdep_assert_held(&pstore_blk_lock);
	if (psblk_bdev && MAJOR(psblk_bdev->bd_dev) == major) {
		psblk_unregister_do(&dev);
		psblk_put_bdev(psblk_bdev, holder);
		blkdev_panic_write = NULL;
		psblk_bdev = NULL;
	}
}

/**
 * unregister_pstore_blk() - unregister block device from pstore/blk
 *
 * @major: the major device number of device
 */
void unregister_pstore_blk(unsigned int major)
{
	mutex_lock(&pstore_blk_lock);
	__unregister_pstore_blk(major);
	mutex_unlock(&pstore_blk_lock);
}
EXPORT_SYMBOL_GPL(unregister_pstore_blk);

static void __exit pstore_blk_exit(void)
{
	mutex_lock(&pstore_blk_lock);
	if (psblk_bdev)
		__unregister_pstore_blk(MAJOR(psblk_bdev->bd_dev));
	mutex_unlock(&pstore_blk_lock);
}
module_exit(pstore_blk_exit);

MODULE_LICENSE("GPL");
MODULE_AUTHOR("WeiXiong Liao <liaoweixiong@allwinnertech.com>");
MODULE_AUTHOR("Kees Cook <keescook@chromium.org>");
MODULE_DESCRIPTION("pstore backend for block devices");